demo09/index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <script src="../build/react.development.js"></script>
    <script src="../build/react-dom.development.js"></script>
    <script src="../build/babel.min.js"></script>
  </head>
  <body>
    <div id="example"></div>
    <script type="text/babel">
      class Input extends React.Component {
        constructor(props) {
          super(props)
          this.state = {
            value: 'Hello!'
          }
          this.handleChange = this.handleChange.bind(this)
        }
        handleChange(event) {
          this.setState({ value: event.target.value });
        }
        render() {
          var value = this.state.value;
          return (
            <div>
              <input type="text" value={value} onChange={this.handleChange} />
              <p>{value}</p>
            </div>
          );
        }
      }
        
      ReactDOM.render(<Input/>, document.getElementById('example'));
    </script>
  </body>
</html>